The coat looks fluid enough to be devore´ velvet. Astrakhan fur was very expensive and luxurious but imitation astrakhan fur was also being manufactured at this time. I have seen illustrations from the early part of the 1920’s where astrakhan (astrakan) fur – real or imitation – is used as a lining as here http://tinyurl.com/bgl5lpx and you see it used as a trim during that decade.

Just wanted to add my two cents! Love the picture! I believe it is broadtail lamb trimmed with sable! Broadtail is often described as having a silky texture and fine moiré or watered-silk pattern. I consider the trim sable, because of the ‘white tipping’ in the photo. I thought the ‘tipping’ was to illustrate the silvery sheen or lack of pigmentation on the gaurdhairs of sables!
Both would be outrageously expensive (then and now) and compliment each other! And if I remember correctly, persian lamb was quite popular at this time and into the 40’s!
Hope everyone has a Happy New Year!
April